Optical probe for fluid light transmission properties

ABSTRACT

Radiant energy is transmitted to a probe element including an interior conical reflecting surface and a fluid sample chamber. Portions of the light which have been transmitted, partially attenuated, or scattered by a fluid sample in the sample chamber are directed by at least a portion of the interior conical reflecting surface to means for collecting the transmitted, partially attenuated, or scattered light. A stilling valve incorporated into the probe element enables elimination of entrained gas bubbles from the chamber.

RELATION TO OTHER APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/514,061, filed 24 Apr., 1990, now U.S. Pat. No. 5,181,082, which is acontinuation-in-part of application Ser. No. 07/330,533, filed 30 Mar.1989, now U.S. Pat. No. 5,007,740.

TECHNICAL FIELD

This invention relates to optical probes for sensing fluidcharacteristics optically, and particularly to optical analysis of afluid sample in a sample chamber. More particularly, the presentinvention is directed to a combination optical probe and stilling wellfor optical sampling of a fluid admitted to a sample chamber.Improvements to this class of the probe include increasing themanufacturability, reliability, efficiency, and reduce the cost of thisclass of probe. Additional features include increased sensitivity,providing a wider practical range of sample materials and wavelengths ofoperation. The need for probe-mounted electronics is also eliminated,thus vastly increasing the ease with which the probe may be cleaned andsterilized. Additional improvements facilitate such cleaning andsterilization, and improve maintainability of the probe.

BACKGROUND OF THE INVENTION

As the advantages of fiber optic based communication and control ofindustrial processes becomes better known, increasing emphasis is beingplaced on various methods of simple, inexpensive, and reliablecommunication of optically sensed physical parameters, or measurands.Optical analysis of certain fluid materials offers known improvementsover other techniques.

The measurement of the light transmitting or light scattering propertiesof a fluid ordinarily requires that a beam of light or radiant energy bepassed through the fluid and subsequently directed towards a radiantenergy detector. Optical apparatus for accomplishing this task have beenused in which discrete components such as lenses, mirrors, or internallyreflecting light guides are employed for the sampling apparatus. Opticalfibers may be used to convey the light to the sensing apparatus and backto detection equipment. Examples of such techniques are illustrated inU.S. Pat. Nos. 4,591,268 to Lew ('268); 4,320,978 to Sato ('978); and4,152,070 to Kushner et al ('070). These methods are generally unsuitedfor direct submersion within the test fluid because the optical surfacesare derogated by fluid contact, i.e., dirt erosion, pitting, anddissolving of the surfaces.

The use of fiber optic light guides is recognized for permitting themeasurement of the light transmitting or scattering properties of fluidsin harsh environments, such as a process container or pipelinecontaining the fluid of interest. Thus, U.S. Pat. Nos. 4,040,743 toVillaume et al ('743) and 4,561,779 to Nagamune et al ('779) depictapparatus for the in-situ measurement of fluid suspensions. A similarapproach described by H. Raab in Technisches Messen, 50, 1983(12), p.475, is employed for the in-situ assay of certain fluids. A commonfeature of these known methods is the use of relatively small prismshaving planar surfaces which act to bend a light beam through 90degrees. Such prisms can be expensive to fabricate and difficult toalign.

Conical reflecting elements have been previously described in theliterature (cf. M. Rioux, et al, Applied Optics, 17(10), 1978, p. 1532).Their use has been primarily as imaging devices for objects disposedalong the conical reflecting element's axis of revolution. As willbecome evident from the subsequent disclosure, the method and apparatusof the invention described herein depart from these known configurationsand permit utilization of the interior conical reflecting surface in anoff-axis manner.

In addition, since the present invention has application in thefermentation arts, it is useful and often necessary to minimize bubblesin the measurement area. Known passive bubble reducing techniques areinadequate when applied to a fermentor environment. Typically intricateand narrow passageways designed to promote drainage of foamy samples areineffective, and may be prone to blockage from the solution, which istypically cell-laden.

For this reason, the present invention comprehends the inclusion of avalved still well or stilling chamber from which the bubbles and foamare effectively drained prior to measurement. The combination probe thusincorporates a stilling well chamber, which may be either electricallyor pneumatically valved, and a novel optical probe. Such a valved stillwell embodiment includes an `open` position in which the solution isfree to pass through the measurement chamber, and a `closed` position inwhich the bubbles and/or foam in the solution are permitted to drainbriefly before the measurement.

For the purposes of this limited description, "fiber optic" "opticalfiber", "light guide", and "radiant energy pathway" refer to opticalcommunication paths, generally optical fibers. As used herein, the terms"radiant energy" and "light" are used interchangeably to refer toelectromagnetic radiation of wavelengths between 3×10⁻⁷ and 10⁻⁹ meters,and specifically includes infrared, visible, and ultraviolet light. Forsimplicity, such electromagnetic radiation may be referred to as simply"light." These terms specifically include both coherent and non-coherentoptical power. "Monochromatic" refers to radiant energy composedsubstantially of a single wavelength. "Collimated" light refers toradiant power having rays which are rendered substantially parallel to acertain line or direction.

SUMMARY OF THE INVENTION

It is an object of this invention to provide improved apparatus for theintroduction and collection of radiant energy into, through, and from asample chamber.

Another object of the invention is the incorporation of a stillingmechanism to rapidly and effectively eliminate bubbles and/or foam in afluid sample at the time of the measurement.

Further objectives include provision of methods and apparatus which areboth cost-effective and capable of withstanding harsh processconditions.

A further object of the present invention is that it is to be easily andinexpensively manufactured.

The probe of the present invention is directed to using an interiorconical reflecting surface to direct radiant energy into and out of asample chamber. The apparatus of the present invention can utilize theconical reflecting surface off-axis. The invention broadly includesopto-mechanical components which carry light from a radiant energysource to a sample chamber, direct this light into the chambercontaining a test fluid sample, and collect and redirect light which hasbeen transmitted, partially attenuated or scattered by the sampletowards a radiant energy detector.

The probe uses optical methods and apparatus for simplified remotemeasurement of the light transmitting or light scattering properties ofa fluid, especially when it is necessary to confine the fluid to itsnatural process vessel, a pipe, or where environmental factors such asexcessive temperature preclude the possibility of siting light sourcesor detectors in the immediate vicinity of the fluid. The inventionfacilitates measurement of fluid properties over a broad range ofapplications, including but not limited to the determination ofdissolved impurity levels in process fluids, the turbidity of fluidssuch as the undissolved solids content of fermentation systems orparticle sizing. Other measurements include filter bed breakthrough,water quality, carbon dioxide in beverages, sugar in organics, water ingasoline, methanol in gasoline, sulfates and phosphates in water, andthe like.

The method and apparatus of the present invention are broadly directedto opto-mechanical components which carry light from a radiant energysource to a sample chamber containing a test fluid of interest, directthis light into the sample chamber and collect and redirect the lightwhich has been transmitted, partially attenuated, or scattered towards aradiant energy detector.

More particularly, the apparatus is a probe for optically sampling afluid in a test or sample chamber, which apparatus includes a source ofradiant energy, an interior conical reflecting surface segmentsurrounding part of a sample chamber, a first portion of whichreflecting surface is used for directing radiant energy through thesample chamber, another portion of the conical reflecting surface isused for collecting radiant energy from said chamber, a first pathwayfor conveying radiant energy to the first portion of the conicalreflecting surface, and a second pathway for conveying radiant energyaway from said sample chamber, via another portion or other portions ofthe reflecting surface, to a detector.

A feature of the present apparatus is the use of an interior conicalreflecting surface to direct radiant energy into and out of the samplechamber. The conical reflector segment permits rapid, economicalassembly and alignment of the optical elements, and improves theefficiency with which the light is transferred into and from the samplechamber.

Measurement of fermentation characteristics and fluids containingbubbles or foam which would obscure the measurement is facilitated byincorporating stilling apparatus in the probe design to enableelimination of such bubbles and/or foam in order to enable accuratemeasurement of the desired solution characteristic. This aspect of thepresent invention therefore includes a sample chamber (which may belongitudinally oriented) having at least one upper vent port, one ormore lower side drain ports, and valve means to close the lower sidedrain port or ports. The valve may be either pneumatically orelectrically operated; electric operation is preferred.

Improvements in the stilling apparatus include improved reliability andmaintainability, and enable relatively easy cleaning of the interiorportions of the probe, as well as the valve plunger which is used toseal the chamber. Another advantage of the present improved probe isrefelected in that the diameter thereof becomes genereally smallertowards the distal end thereof, faciliting entry of the probe into agallery. The probe can readily be sized for entry through a conventionalcontainer aperture of about 25 centimeters.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Numerous other features and advantages of the invention disclosed hereinwill be apparent upon examination of the several drawing figures forminga part hereof. Solid line arrows may be used to indicate light rays. Inall views, like reference characters indicate corresponding parts orelements:

FIG. 1 illustrates in cross-sectional view major portions of an opticalprobe according to a primary aspect of this invention;

FIG. 2 illustrates in cross-sectional view portions of another opticalprobe according to a primary aspect of this invention;

FIG. 3 illustrates an optical probe assembly according to another aspectof the present invention;

FIG. 4 illustrates a transverse section of the invention, takenimmediately below the top seal of the sample chamber, as indicated inFIG. 1;

FIG. 5 illustrates a longitudinal section of the invention shown in FIG.1, further illustrating details of the device;

FIG. 6 illustrates a detail of the device of FIG. 5;

FIG. 7 illustrates a longitudinal section of the invention shown in FIG.2, wherein the probe is permanently mounted;

FIG. 8 illustrates the invention shown in FIG. 2, wherein the probe ispermanently mounted circumjacent a pipe which may be flanged forinsertion in a line;

FIG. 9 illustrates an aspect of the invention in which lenses areemployed to shape the light beam before and after reflection from theinterior conical reflecting surface;

FIG. 10 illustrates another view of the apparatus of FIG. 9;

FIG. 11 illustrates in plan view another aspect of the invention whichsolves the potential problem of stray light;

FIG. 12 illustrates in longitudinal section view the baffle of FIG. 11,incorporating apparatus similar to that of FIG. 2;

FIG. 13 illustrates another view of the baffle according to FIG. 11;

FIG. 14 illustrates an aspect of the invention in which radiant energyis introduced directly into a sample test chamber and scatteredradiation is collected by the interior conical reflector element;

FIG. 15 illustrates alternative apparatus in which radiant energy isintroduced directly into a sample test chamber and scattered radiationis collected by the interior conical reflector element;

FIG. 16 illustrates in cross-sectional view major portions of an opticalprobe according to an improved embodiment of this invention;

FIG. 17 illustrates in detail the main elements of the probe accordingto FIG. 16;

FIG. 18 illustrates electro-optical sensing and detection andpositioning of the optical rod relative the reflective surface accordingto a variation of the probe of FIG. 16;

FIG. 19 illustrates entirely optical sensing and detection andpositioning of the optical rod relative the reflective surface accordingto another variation of the probe of FIG. 16; and

FIG. 20 is an illustrative cross section of the probe showing therelative positioning of the sense and plural detection pathwaypositions, and location of the stilling valve power communicationpassageway.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 through 15 illustrate a preferred embodiment of the presentprobe invention. FIGS. 16 through 19 illustrate the improved probeaccording to another embodiment. Turning now to FIGS. 1, 4, 5, and 6 inwhich a probe 10 incorporating an interior conical reflector segment 11is joined to a lower stilling valve actuator segment 12, to an uppermain body segment 14 having an upper vent hole 15, and which in turn isjoined to an extension tube segment 16. The probe 10 includes an axis ofrevolution 13 of the conical reflector segment 11 which, extended, maybe the center line of the probe 10. The axis of revolution, of course,need not necessarily be the probe center line.

The interior conical reflector segment 11 is made by forming an interiorconical reflecting surface 17 into the central area of a (preferablythick walled and hollow) cylindrical body. An interior conicalreflecting surface 17 reflector segment 11 is easily fabricated by asimple cutting operation on a lathe. A quality reflecting surface 17 isobtained either by fine cutting of the reflecting surface 17 followed bya finish polish or by other well-known optical surface-finishingmethods. A reflective overcoat (not shown) can be deposited to furtherimprove the reflectivity of the reflecting surface 17. It will beappreciated by those skilled in the art that the light transmission andreflection properties of the optical elements described here will beinfluenced by the wavelength or wavelengths of light used to make thesample measurement, e.g., the light scattering or light transmittingproperties of the sample fluid. Further, the probe 10 reflector and mainbody segments 11, 14 may be exposed to the process fluid (F) andtherefore must be chosen so as to withstand the chemical and physicalproperties of their expected environment.

The probe 10 segments 11, 12, 14, 16 are essentially elongated andcylindrical in shape, though another shape may be used. The reflectorsegment 11 incorporates an interior conical reflecting surface 17; thesegments 11, 14, 16 house the optical, electrical (or pneumatic) andmechanical components which carry light from a remotely located radiantenergy source (not shown) to a sample chamber 18 containing a test fluid(F). Sample chamber 18 is formed in the central area joining thesegments 11 and 14. A cylindrical, transparent section of glass, havinga hollow, longitudinal central portion is used. The sample chamber 18extends from above the juncture of the segments 11, 14 to a point belowthe conical reflecting surface 17 within the reflector segment 11. Aprobe 10 central passageway 38 extends above and below the samplechamber 18 in the segments 14, 11 respectively.

A plurality of longitudinal passages such as the light guide passages 28provide access and protection for the light guides 20, 21, 26 enteringthrough the segments 11, 14 and portions of the segments 12, 16. Thesepassageways 28 additionally provide for precise alignment of the lightguides 20, 21, 26 at the desired radial angle and radial distance fromthe centerline of the segment 14 corresponding to the axis of revolution13 of the reflector segment 11. Wires (not shown) communicate electricalpower needed to actuate the valve mechanism via passageway 29. Pneumaticcommunicating passageways may be substituted as appropriate.

The segments 14, 16 may be joined in a sealing manner as is known tothose of skill in the art, including welding or by adhesives. The use ofconcentric, stepped counterbores on the segments 14, 16 facilitatemechanical alignment of the segments.

Similarly, the segments 11, 14 may be joined by concentric, steppedcounterbore features (as are more clearly shown in detail FIG. 6).Attachment of the interior conical reflector segment 11 to the uppermain body segment 14 may be effected by a circumferential weld. Thesample chamber 18 has a transparent wall 25 disposed between the conicalreflector segment 11 and the upper main body segment 14. Prior tojoining, the transparent wall 25 (which is a cylindrical section andformed of a strong transparent material such as high strength, hightemperature glass), is inserted centrally of these two segments (11, 14)which are then held together with a pressure force suitable forcompressing circular or O-ring seals 31, 32 to the desired state ofcompression for effecting sealing against leakage of the sample fluid.Axial alignment of the reflector segment 11 and the main body segment 14is accomplished by the mating surfaces 33 and 34 which consist of astepped counterbore 35 fitted with the main body segment 14 bore 36, theinternal diameter of which is no smaller than the external diameter ofthe step 37 machined into the outside diameter of the reflector segment11. This mating configuration shown is for illustration only and is notintended to be a limitation of the appended claims, as other equallyconvenient configurations for aligning and joining the segments known tothose of skill in the art may be substituted.

FIG. 4 reveals the interior section of upper main body segment 14 nearthe top of sample chamber 18, showing the centerline of segment 14,which is also the axis of revolution 13 of the interior conicalreflector segment 11. The first, second, and additional light guides 20,21, 26 pass through this section. The cylindrical transparent wall 25forming the sample chamber 18 within the segment 14 includes a pluralityof light guide passageways (shown enlarged for emphasis only) 28surrounding light guides 20, 21, 26 through the segment 14. A furtherpassageway 29 surrounding the electrical/pneumatic communicatingpassageway to stilling valve actuator segment 12 (not shown in thisview) bears the necessary actuation control lines to the stilling valvesegment 12.

Turning now to FIG. 5, the reflecting properties and cylindricalsymmetry of the conical reflecting surface 17 enable rapid, simple, andcomparatively inexpensive manufacture of the novel measurement probe 10reflector and main body segments 11, 14 incorporating this reflectingsurface 17. The segments 11, 12, 14, 16 are disposed along alongitudinal axis which serves as the axis of revolution 13 of thereflector segment 11; an upper vent hole 15 extends upward from thesample chamber 18, defined by a transparent wall section 25, andcommunicates to the upper port 30, where the sample fluid (F) freelyexits from one side of the main body segment 14 above the sample chamber18. While this embodiment is illustrated by a single such upper port 30,a plurality of such ports may also be employed.

The reflector segment 11 contains one or more process fluid (F) lowerports 39. The lower ports 39 communicate the process fluid (F) directlythrough the central passageway 38 thence to the upper port 30.

In a preferred embodiment, the reflector segment 11 includes in itslower end certain portions of a valving apparatus which permit thesample chamber 18 to intermittently function as a novel still well aswell. More particularly, there is formed in the lower end of thereflector segment 11 a valve seat or stop 40, in the form of aconstriction in the cross sectional diameter of the central passageway38 in the reflector segment 11. The valve stop 40 enables interruptionof the free communication of process fluids (F) from the lower port orports 39 through the sample chamber 18 to the upper port 30 via a vent15.

A stilling valve actuator segment 12 is responsible for closing thestilling valve formed by the valve seat or stop 40 in the reflectorsegment 11 and by a plunger 41, which is located in the centralpassageway of the actuator segment 12. The plunger is sealingly shapedto join with the stop 40 and thus close central passageway 38. Power foractuating the plunger 41 is shown in this example as electro-magneticvia a solenoid coil 42; pneumatic drive means may be substituted suchthat the plunger 41 closes with the stop 40 by pneumatic pressure.Solenoid coil 42 coacts magnetically with a permanent magnet 43 embeddedin the plunger 41, causing the plunger 41 to close the centralpassageway 38 at the valve stop 40. The plunger 41 preferably includes aplurality of arcuate ridges 44, 45 to ensure proper coaxial alignment ofthe plunger 41 with respect to valve stop restriction 40. Wires (notshown) communicate the electrical power to actuate the valve mechanism40, 41 via the coil 42.

The valve actuator segment 12 may be attached to the reflector segment11 in a manner substantially similar to that in which the reflectorsegment 11 is joined to the main body segment 14, previously described.

The plunger 41 is retained within the actuator segment 12 by placementof a bottom cover 46 over the lower end of the actuator segment 12; oneor more process fluid drain holes 47 may be included in the bottom cover46 to permit essential drainage and to avoid hydraulic restriction onthe free movement of the plunger 41 to close the valve plunger 41 toseat 40.

A simplified reflector segment is shown in FIGS. 2 and 3. The more basicprobe 19 (FIG. 2) having a similar reflector segment 92, the inclinationangle alpha 1 of the conical reflecting surface 17 is about 45 degreesin the preferred embodiment. The main body segment 14 houses opticallight guides 20, 21, 26. The light guides 20, 21, 26 extend along thelength of the main body segment 14, being terminated in close proximityto the reflecting surface 17. Additional light guides 26, 27 may bedisposed at various angles relative light guide 20.

A detailed description of the reflector segment 92 relating to lightreflecting characteristics of the reflective surface 17 follows,illustrating optical operation of the generic optical probe 19 accordingto the present invention. Light from a remote source (not shown) iscommunicated to the probe 19 via a first optical fiber 20. The fiber 20is positioned in and by the passageway 28 (FIG. 4) in the main bodysegment 14 and is terminated adjacent the conical reflective surface 17.The conical reflective surface 17 directs this light into and throughsample chamber 18, and collects and redirects the light which has beentransmitted, partially attenuated, or scattered. Other optical fiberssuch as the fiber 21 convey the light towards a remotely located radiantenergy detector (not shown).

Additional fibers 26, 27 may be positioned off-axis to receive light.

A ray of light traveling along the optical axis of this system,originating in the light guide 20 and transmitted to the light guide 21is composed of a series of light ray segments 22, 23, 24 for the conicalreflector segment 92 having a reflecting surface 17 and an inclinationangle of about 45 degrees. The initial light ray portion 22 representsthat portion of the light ray leaving light guide 20 and incident on afirst surface area of the reflecting surface 17 while the sampling lightray 23 denotes that light ray portion which is reflected through anangle of about 90 degrees and passed through a section of the samplechamber 18 transparent wall 25, where the light sampling ray 23encounters the test sample fluid (F).

After being passed through the sample fluid (F) and the opposite samplechamber 18 wall 25, the sample ray 23 encounters a second surfaceportion of reflecting surface 17 and is again deflected through an angleof about 90 degrees to form an exit light ray 24. The light ray segment24 represents a continuation of the ray 23 from the second portion ofreflecting surface 17 to and incident upon light guide 21. FIG. 3 showsthe apparatus of FIG. 2 in the plane which contains the light raysegment 23 and which is perpendicular to the axis of revolution 13 ofthe conical reflector segment 92.

The additional light guides 26, 27 can serve either as collectors oflight originating from guide 20 or they can function as light conduitsfor other external light sources when such are required. When used aslight conduits, the additional light guides 26, 27 receive lightscattered substantially from the center of sample chamber 18. If theangle alpha 2 is 90 degrees, the configuration is termed nephelometricand the probe may advantageously be used as a nephelometric turbidityprobe. The additional light guide 26 collects that light originatingfrom the light guide 20 which light is subsequently scattered by thetest fluid (F). The angle Alpha 3 is shown as approximately 55 degrees.In combination, the light guides 20 and 21 permit the measurement ofeither the forward- scattering component of the turbid media or theattenuation of radiant energy as a function of the number density ofdissolved materials in an otherwise homogenous fluid.

Several alternative embodiments of an optical probe using the conicalreflective surface are shown in FIGS. 7 through 15. The simplifiedoptical probe 48 of FIG. 7 is adapted for permanent mounting on avessel, such as a process vessel or storage tank 50, only a portion ofwhich is shown. A peripheral flange 51, attached to the probe 48 (as forexample, by a circumferential weld ring 52) illustrates how the probe 48may be secured to the process vessel 50. A simplified probe similar tothe probe 92 shown in FIG. 2 is illustrated. The process vessel 50 may,for example, be a container of fixed size or a pipeline, which canaccommodate the length of the probe 48 exposed to the process fluid (F).A sealing means, such as a circular or O-ring seal 53 can be used toprevent the fluid (F) from leaking to the outside environment.

Alternatives for effecting such seals are known to those skilled in theart; the O-ring of this embodiment is not limiting and does not precludethe use of alternative seals. An adequate seal between the samplechamber 18, the reflector segment 90, and the main body 14 may beaccomplished with the aid of two O-ring seals 31, 32, glass-to-metalgraded seals or the like. These elements may be joined and sealed aspreviously described. The process fluid (F) is permitted to flow freelythrough the sample chamber 18 via a lower port 54 and one or more upperports 30. The measurement process is as previously described; it may becontinuous or intermittent with the addition of still well valvingapparatus.

FIG. 8 depicts another embodiment of the invention. An optical samplingapparatus includes a probe body 55 which contains the conical reflectorsegment 91 and the light guides 20, 21. It is configured such that theconical reflector segment 91 fits over a pipe section 56 (at least aportion of which is transparent at the sample chamber site) which can inturn be coupled to a sample line (not shown) by one or more end flanges57. In this embodiment, a single service cable 58 contains all of theoptical light guides 20, 21.

Referring briefly again generally to FIGS. 2 and 3, light leaving thelight guide 20 includes light rays whose maximum inclination angle withrespect to initial light ray portion 22 are determined by the numericalaperture of the light guide 20; all rays having inclination angles lessthan this maximum inclination angle define an acceptance cone of lightwhich may be transmitted into the light guide 21. Because of this, theplurality of rays striking the reflection surface 17 will result in skewrays through the sample chamber 18, not all of which skew rays will fallwithin the acceptance cone of the light guide 21 after deflection fromthe reflecting surface 17 upon exiting the sample chamber 18. Thiscircumstance reduces the maximum radiant energy which traverses thesample chamber. In certain applications, such loss of radiant energy isnot serious since one can choose among available light sources, lightguides, and radiant energy detectors, the accumulated sensitivities andlosses of which, when combined, yield a favorable measurementsensitivity.

A further improvement of the embodiment of the invention depicted inFIGS. 2 and 3 addresses the decreased measurement sensitivity situationdescribed above; the optical scheme of FIG. 9 promotes more efficienttransfer of light through the sample chamber 18. Additionally, thisembodiment results in optical rays the passage of which through a testfluid (F) is affected less by changes in the refractive index of thefluid, such as might result from changes in temperature for example.

Specifically, the individual lenses 59, 60 are interposed between theends 61, 62 of the light guides 20, 21, respectively. The lens 59 servesto substantially collimate the light leaving the light guide 20 and thecollimated beam is in turn imaged (by the reflecting surface 17) at thecenter of the sample chamber 18, substantially independent of the indexof refraction of the test fluid (F); this is shown even more clearly inFIG. 10, where the sampling light ray 23 is perpendicular to the axis ofrevolution 13 of the reflector segment 92. The incoming light rays andoutgoing return light rays are represented collectively as light beamdiameters 63, 64, respectively. The return light beam 64, incident onthe lens 60 is re-imaged onto the end (i.e., input face) 62 of the lightguide 21. The longitudinal line image, formed at the center line (oraxis of revolution 13 of the reflector segment 92) of the sample chamber18 has a length substantially equal to the diameter 63 (and also thediameter 64).

In certain uses it will be desirable to eliminate or reduce stray light.Those of skill in the art will appreciate that a limitation to manyoptical-based measurement systems is the presence of stray light, whichby definition, is that light which reaches the detector by paths otherthan that intended. As an example, in turbidity measurements, excessivestray light may limit sensitivity when analyzing for low levels ofsuspended matter. One way to minimize sources of stray light in anoptical probe is shown in FIGS. 11, 12, and 13. A stray light baffle 70may be used to eliminate or reduce stray light. Such a baffle 70 limitsthe angle of passage of light through the test chamber 18 wall 25.

An additional light path via the lens 65 is positioned approximatelynormal to the optical axis (defined by the light ray 23 in FIGS. 2 and9) and passing through the center of the sample chamber 18. Thisconfiguration may be employed for measuring very low turbidity levels,but may also be appropriate for Raman spectroscopy. A portion of thelight scattered by matter in the sample fluid (F) volume near a point,for example the centerline and axis of revolution 13, is directedtowards the collection lens 65. The light rays 66 comprise this light.Stray radiation such as that indicated by a wavy line light ray 67 mayalso reach the lens 65 if the conical reflecting surface 17 is notperfectly smooth, so that light incident upon it from the lens 59 may bescattered by surface defects into many directions, only one example ofwhich is illustrated by the wavy line light ray 67. One of ordinaryskill will appreciate that the light ray 67 does not actually travel inthe curvilinear fashion indicated but rather is illustrative in nature.The presence of such rays reaching the collection lens 65 and from therevia the light guide 26 to the appropriate detection means (not shown)implies that in the absence of any scattering material in the testchamber 18, a finite signal is produced. This signal, if large enough,can adversely limit the sensitivity of the device and make a precisemeasurement of low concentrations quite difficult.

To eliminate this difficulty, a circular light restricting baffle 70including a plurality of radially extending passageways 71, 72, 73 isinterposed between the reflective surface 17 of the reflector segment 92and the main body segment 14, which latter segment contains the lenses59, 60, 65 and the respective light guides. Baffle 70 includes apassageway 71, which permits light from light guide 20 to passunobstructed into sample chamber 18 after collimation by lens 59.Another radial passageway 72 permits the directly transmitted beam topass through unobstructed to the lens 60, and a third radial passageway73 of the baffle 70 permits light scattered by the sample to pass onfurther to the lens 65. However, baffle 70 prevents stray light rayssuch as the stray ray 67 from reaching the lens 65 except via the baffle70 passageways 71, 72, 73 and the sample chamber 18. A plan view of thebaffle 70 is shown in FIG. 13. By varying the size and shape of thepassageways created in the baffle 70, it is further possible to controlsuch factors as how much light is collected by the lens 65 for purposesof controlling the collection angle of light.

FIG. 14 illustrates yet another embodiment of the invention wherebylight is introduced along the longitudinal central axis 13 of thecylindrical sample chamber 18; that light which is scattered at 90degrees is collected by the reflecting surface 17 and directed towardsone or more receiving light guides, illustrated by the light guides 20,21. Here, the light guide 26, contained within a protective sheath 77carries light to the sample chamber 18 where it passes through aprotective, transparent window 78. The light beam 79 emerging from thewindow 78 is scattered at various angles. The assembly and constructionof the configuration illustrated in FIG. 14 is substantially the same asthat previously described except that the incoming light is introducedalong the longitudinal axis and collected normal thereto. In particular,the light rays 80 and 81 illustrate light rays which have been scatteredat about 90 degrees with respect to the incident light beam 79 by thetest fluid (F). The approximately 90-degree scattered radiation isdirected towards a plurality of collecting optical fibers 20, 21 byconical reflector segment 93 reflecting surface 17. Here, segment 93 isopen-ended and truncated to permit free flow of the sample into thesample chamber. Again, the sample chamber 18 is disposed between theO-ring seals 31, 32 while a lower port 84 and an upper port 85 permitfree exchange of test fluid (F) within the sample chamber 18. A lenscould be interposed between the light guide 26 and the window 78 (orsubstituted for window 78) whereby the shape of the outgoing beam 79could be adapted to a wide variety of measuring requirements; thus thepoint of maximum energy concentration within light beam 79 could beextended further beyond window 78 by suitable choice of lens power.

A still further embodiment of this present invention is disclosed inFIG. 15, where light is introduced along the longitudinal axis and inwhich transmitted radiant energy may be collected by at least oneadditional light guide 27, as well as scattered light being collected bylight guides 20, 21. In this case, the sample chamber 18 isself-contained and an additional port 87 is added to permit the testfluid (F) to flow through the sample chamber 18. The assembly andconstruction of the configuration illustrated in FIG. 15 issubstantially the same as that previously described. Reflective segment94, however, is closed below port 87.

Thus, as described above, this invention provides a method and apparatusfor simplifying the introduction of light into and from a sample chamberfor the purposes of monitoring changes in the transmitted, attenuated,or scattered radiant energy passed through the sample chamber.

Another embodiment of the probe is illustrated in FIGS. 16-20.Externally, the optical probe 100 is similar to probe 10 of FIGS. 1 and5 with improvements to segment 102 and a cover 104 therefor, andimprovements to the main body 106, incorporating therein the function ofboth segments 14 and 16 of FIGS. 1 and 5 in a single integral unit. Anadditional improvement in manufacturability results from sealing thesegments with O-ring seals and joining the segments relativelypermanently, but separably, with strong adhesives. The cross sectionalprofile of probe 100 varies from that of probe 10 in FIGS. 1 and 5,becoming progressively smaller, rather than larger, towards distal endat segment 102. The probe internals are shown in greater detail in FIG.17, wherein main body 106 houses a pair of wires 108 joined toelectrical-to-optical transition stage 110 or alternatively an opticalpathway 112 is connected to optical-to-optical transition stage 114.Optical pathways contained within protective tubes 116 and 118respectively, efficiently carry the optical signal to and/or from thetest chamber, as described hereinafter. Main body 106 is preferablycylindrically shaped about a longitudinal axis (axis 120 of FIG. 20) foreasy entry into an aperture in the line or vessel wherein the samplefluid is measured. An O-ring seal 122 is provided in peripheral groove124 for sealing the instrument in the aperture. Other sealing structuresmay be substituted, as known to those of ordinary skill in the art.

The segments 106, 102, and cover 104 are preferably made of stainlesssteel or an equivalent strong, durable, and corrosion-resistantmaterial; they are elongated, and cylindrical in shape, and preferablyincorporate matching concentric, stepped counterbores 126, 128, and 130,132 as indicated at 134, 136, and 138. Axially spaced along thesecounterbore junctions are suitable grooves for holding a series ofO-ring seals 140, 142, and 143, or such equivalent seals as are known inthe art. Cover 104 may be assembled over segment 102 before or afterjoining segment 102 to main body segment 106.

The segments 106, 102, and cover 104 may be joined together at sites134, 136, 138 in a sealing manner as is known in the art; adhesives arepreferred, although threaded components or welding may also be used.Sealants and threaded members more readily enable removal formaintenance operations. However, sealants must be carefully selected,giving due consideration to the materials selected for the segments 106,102, and cover 104, to the temperatures which the probe is to besubjected in use, and to the fluids in which the probe will be immersed.Specifically, one part, oven-cured, expoxy bonding adhesives such asUniset® 1962-31 sealant, from Emerson Cuming, are suitable. Thisadhesive bonds stainless steel, and is believed acceptable for long-termcontact with food and drugs.

The segments may be separated after sealing by subjecting the sealant toits release agent or by heating the joint above the temperature at whichthe sealant breaks down. The release agent for Uniset® 1962-31 sealantis ECCOSTRIP® 93 from the same manufacturer. The breakdown temperatureof Uniset® 1962-31 sealant is above 800° F. It is an important advantageof the present embodiment that, by increasing the optical efficiency ofthe probe, the need for electronics amplification and signal processingstages located within the probe has been substantially eliminated,permitting the heating of the sealant adhesive to these hightemperatures. That is, absent the present optical improvements,electronics circuitry which would otherwise likely be necessary isavoided, making it possible that the probe joints can be heated abovethose temperatures at which electronics packages normally fail.

Joining by use of threaded segments requires careful alignment such thatlongitudinal passageways are properly aligned. Welding maximizesdifficulty in maintenance and repair as it becomes difficult to enterthe probe cavity.

Main body segment 106 includes a generally longitudinal main passagewayforming an interior cavity 146 which is terminated in an end wallforming cavity bottom 148 and smaller longitudinal passageways 150 and152 to guide the respective optical pathways to the sample chamber area,as will be described subsequently. The main body 106 also includes afluid passageway terminating in at least one exterior upper vent hole154 similar to upper vent hole 15 in FIGS. 1 and 5. One or moreadditional longitudinal passageways for additional optical pathways(shown in FIG. 20) may also be included. One or more longitudinalelectrical wire or pneumatic passageways are required when a stillingvalve is included, as in segment 102 of the present embodimentillustrated in FIGS. 16-20. Another segment, not shown, may be joined tomain body 106 with the internal threads 156 at the extreme proximal end.A seal 158, such as an O-ring seal, may be used to seal this segment tomain body 106. While it is noted that the main body cavity may be largeenough to hold electronics circuitry or the like, the present designspecifically succeeds in increased sensitivity in order to eliminate theuse of such temperature sensitive additions to the probe.

Segment 102, attached at the distal end of probe 100 and facing the mainbody segment 106 includes, according to the embodiment of FIGS. 16-20,an integral interior conical reflecting surface 160 formed in theproximal end of segment 102. This surface 160 is of a shape which issubstantially similar and functionally equivalent to the formation ofthe interior conical reflecting surface 17 of the first embodiment, asseen for example in FIG. 6. However, the manufacturability of theinterior conical reflecting surface 17 and the precise alignment thereofduring assembly has been significantly enhanced in the embodiment ofFIGS. 16-20 by forming the interior conical reflecting surface 160 as anintegral element of segment 102. Surface 160 is formed in the proximalend of segment 102. Spaced from the surface 160 towards the distal endof segment 102 is a peripheral groove 162 about the longitudinal axis ofthe segment. This groove carries the solenoid coil 164 winding when anelectrical solenoid stilling valve is used, as described in greaterdetail hereinafter. An axial bore 166 extends the full length of segment102, and communicates with the distal end of the sample chamber and withupper vent hole 154.in main body 106 at its proximal end. Axially spacedalong this bore and longitudinally spaced a short distance from thesample chamber is a necked-down area which provides a valve seat 168 forthe stilling valve included in this illustrative example, and which issubstantially similar to valve seat 40 of the first embodiment.

Main body segment 106 includes a central recessed bore in the distal endthereof adjacent segment 102 for enclosing the transparent chamber wallcylinder 170, which may be of glass or such other material as describedearlier in connection with FIGS. 1-15. The cylinder 170 is positionedradially by the aforementioned bore and by respective proximal anddistal O-ring seals 172 and 174, which tightly seal the chamber andposition cylinder 170 therebetween. Details of this configuration aredescribed above in association with the embodiments described in FIGS.1-15. Other seals may be substituted as known to those skilled in theart.

The stilling valve actuator is responsible for closing the stillingvalve formed by the valve seat 168 or stop and by a plunger 176, whichis located in axial bore 166, the central passageway through segment102. The plunger 176 is sealingly shaped to join with the seat 168 andto thus close axial bore 166. Motive power for actuating the plunger isshown, in this example, as being provided electromagnetically via asolenoid coil 164; as with the embodiments illustrated in FIGS. 1-15,pneumatic drive means (not shown) may be substituted such that theplunger 176 closes with seat 168 by pneumatic pressure. Solenoid coil164 coacts magnetically with a permanent magnet end 178 of the plunger176, causing the plunger to close the axial bore 166 central passagewayat the valve seat 168.

The source of the magnetic force may be contained within plunger 176 asshown in the first embodiment (FIG. 5) or may be or include a magnetizedregion, such as plunger ridge 178. The plunger 176 preferably includesone or more radial ridges 178, 180, 182 to ensure proper coaxialalignment of the plunger with respect to the valve seat restriction.Wires (not shown) communicate between coil 164 and a power sourceexternal to the probe to actuate the valve mechanism via the coil 164;the wires pass through the probe as shown in FIGS. 1-15.

An ordinary coil spool cannot be used to retain and protect the windingin the configuration shown in FIGS. 16-17; since thinly insulated wiresare required, one or more lengths of protective insulation padding, suchas insulated tubing, may be used to protect the winding entry and exitturns from shorting to the body of segment 102.

The plunger 176 is retained within the distal end of segment 102 by athreaded adjuster 184. Adjuster 184 includes a plurality of externalthreads which mate with threads 186 inside the distal end of segment102; one or more longitudinal fluid passageways can be provided throughadjuster 184 to permit relatively free fluid entry into the samplechamber stilling well. Deep longitudinal grooves can also be used forthis purpose. While such passageways are preferred in this example, thepresent invention is not to be limited thereto. Such free fluid flowpermits essential drainage and avoids hydraulic restriction on the freemovement of the plunger to close the valve plunger to its seat. Aplurality of communicating fluid passageways 188 are used, as seen inFIGS. 16 and 17, to permit free fluid entry and exit into the plungerchamber and into the sample chamber.

The respective top and bottom drain ports 154 and 188 function asdescribed to promote free exchange of the test chamber fluid contentswith the bulk sample. This arrangement leads to several samplingadvantages. As with the embodiments of the invention illustrated inFIGS. 1-15, the enclosed chamber prevents large disruptions of theoptical beam either by entrained air or by fluid level fluctuations suchas may occur due to rapid stirring of the sample. Second, bubbles whichdo pass through the enclosed chamber shutter the optical beam for only abrief period; use of the stilling scheme is effective in minimizingthese disturbances. In some mounting configurations, the main chamberwall can be disposed parallel with the fluid flow; there is thus littletendency for bubbles to accumulate on these surfaces, which wouldotherwise lead to erratic reductions in the dynamic range of themeasurement. The stilling valve is otherwise effective in minimizingthese bubbles. Accumulated solid matter may be removed by cleaning whenneeded.

Fluid flow for operation of the probe is substantially as describedpreviously in connection with FIGS. 5, 7, and 10. The probe 100 canoften be disposed such that the optical path through the fluid lies in aplane perpendicular to the flow of fluid within the sample chamber,i.e., the longitudinal axis of the probe. The subject fluid is passedthen through the probe 100. Shortly before a sample is to be taken andmeasured, the stilling valve solenoid is actuated by passing anelectrical current through the solenoid coil 164 such that the magneticfield of the plunger magnetic end 178 and the electromagnetic field ofthe coil interact to force the plunger 176 against its seat 168 to closethe stilling valve and seal off the sample chamber. Alternatively, apneumatic pressure force variation can be used to close plunger 176against its seat 168. In either case, entrained bubbles are then free tofloat out of upper vent hole 154 without additions thereto and solidsare permitted to settle out of the optical path in the test chamber.

The embodiment of the invention shown in FIGS. 16-20 includesimprovements in the operation of the stilling valve mechanism; thestructure of the first embodiment was found to be especially sensitiveto set up and adjust for proper closure of the valve, both initially andespecially following maintenance operations such as cleaning. Thisadjustment difficulty was found to be at least partly related tovariations in the strength of the magnet 43 shown in FIG. 5. Theinteraction of the electromagnetic field produced by the coil 42 and thepermanent magnet 43 field achieved less reliable valve closing forcesthan desired in some cases when adjustment was improper. In the presentembodiment this variation in valve closing force is accommodated bymaking the rest position of the plunger (and thus the axial distance oftravel thereof to seat 168) variable.

Correction of this difficulty contributed to greater manufacturabilityof the probe 100. This seat position adjustment is accomplished simplyby inserting a small flat blade such as a screwdriver tip into slot 190in the distal end of threaded adjuster element 184 and turning theadjuster in axial bore 192 within the threaded interior portion of bore192 to position plunger 176 as desired relative the coil 164. Thisadjustment enables the assembler to easily and rapidly select a desiredplunger rest position within a range of acceptable plunger positionswhich provides reliable operation.

In the embodiments of FIGS. 1-15 previously described, optical fiberscarry the optical signal to and from the internal conical reflectingsurface through the main body. Considerable difficulty arises inprecisely aligning the tiny optical fiber relative the internal conicalreflecting surface. The optical fibers must be quite preciselypositioned both axially and radially within the probe, and securely heldin place against movement. In the present invention, both of thesedifficulties are corrected by substituting a large diameter, rod-shapedoptical light pipe of considerable greater diameter, and which also hasmore efficient optical energy transfer characteristics. Thus there isshown in FIGS. 18 and 19 two illustrative variations of the presentinvention in which either combined electro-optic or solely opticalsensing and/or detection may be used. The improvements of the presentinvention considerably increase the facility with which the lightpathways and the internal conical reflecting surface may be preciselyaligned and maintained in such alignment.

For convenience, applicants prefer the electro-optical sensing/detectionscheme used in FIG. 19, rather than the solely optical system of FIG.18. The two variations may be combined, with one serving as a sensor andthe other as a detector, as may be desired in some circumstances. FIGS.18 and 19 also illustrate alternate variations in positioning the end ofthe optical rods 194, 196 with respect to the reflective surface 160.

FIGS. 17 and 19 illustrate the preferred variation of the invention inwhich wires 108 carry the optical sense signal to the probe 100 oralternatively convey the detected signal from the probe. Anelectrical-to-optical transition stage 110 contained within the probe100 main body 106 interior cavity 146 includes a cup-shaped cap 198housing a transducer 200 which is either an electrical light source oran opto-electric device for converting optical energy into electricalenergy, as described hereinafter. Also inserted into the cap 198, andpreferably communicating with the transducer for maximum energyconversion efficiency, is the proximal end of an elongated opticallytransmissive rod 196, such as a glass rod. These rods are sized between0.001 and 0.100 inches and preferably about 0.062 inches, as opposed tothe approximately 400 micrometer fiber optic diameters disclosed inFIGS. 1-15. Suitable other materials may be substituted, as known tothose of ordinary skill in the art. The rod 196 is carried by aprotective and shielding tubular guide 116, which may also extend atleast partly into the cap 198 if desired. The distal end of the rod ispositioned adjacent the internal conical reflecting surface 160 asdescribed hereinafter. Tube 116 carries rod 196 through the elongatedpassageways 152, etc., previously described to a point adjacent theinternal conical reflecting surface 160, which as previously describedis formed in the proximal end of segment 102.

In the FIG. 19 variation of the present embodiment, electrical wires 108communicate the sensing signal to the probe 100. The same configurationmay be used to detect the sensed signal and convey it externally bywires; the difference between the sense and detector configurationsbeing that in the sense configuration, an electro-optical transducer, orlight source is required, while in the electrical detectorconfiguration, a light-to-electrical current transducer is required. Inpractice, a light-emitting diode (LED) can be used as the light source;an infrared or laser LED may be preferred in some measurement schemes.Alternatively, photodiodes can be used. The wavelength of the lightsource can be selected for a desired wavelength for such measurements asare determined to be wavelength-sensitive. Examples of detectortransducers include photocells, phototransistors, and their equivalents.

In operation according to the FIG. 19 configuration, a transducer 200converts light energy to electrical energy or electrical energy to lightenergy when used in the detector or sense configuration, respectively,and an electrical signal is communicated between a remote site and thetransducer 200 via wires 108.

The variation shown in FIG. 18 is an all-optical version generallysimilar to that of the FIGS. 1-15 embodiment with significantimprovements to the mechanical alignment and optical path efficiencycharacteristics. Here, a given optical path between the reflectingsurface 160 and the optical fiber 112 may serve as either an sense ordetect path, as depends on the hardware connected to the remote end ofthe optical fiber 112. Thus FIG. 18 serves in describing both functionaluses: sense and detect, the difference being the source and direction ofthe light. As a sense optical pathway, optical fiber 112 carries theoptical sense energy to a cup-shaped cap 202. A simpleoptical-to-optical transition stage 114 is contained within the probe100 main body 106 interior cavity 146. Transition stage 114 includes acap 202 which houses, and preferably contacts the optical fiber end formaximum transfer efficiency, and the proximal end of an elongatedoptically transmissive rod 194, such as a glass rod similar to rod 196previously described. Again, suitable other materials may besubstituted, as known to those of ordinary skill in the art. The rod 194is carried by a protective and shielding tubular guide 204, which mayalso extend at least partly into the cap 202 if desired. The distal endof the rod is positioned adjacent the internal conical reflectingsurface 160 as described hereinafter. Tube 204 carries rod 194 throughthe elongated passageways 150, etc., previously described to a pointadjacent the internal conical reflecting surface 160, which aspreviously described is formed in the proximal end of segment 102.

FIGS. 18 and 19 also illustrate alternate variations in positioning theend of the optical rod 194, 196 with respect to the reflective surface160.

At the distal end of segment 106 in FIG. 18, rod 194 is stopped fromextending past peripheral abutment 206, which extends radially outwardto precisely position the tip of rod 194. A cavity 208 is formed by thedepression formed by internal conical reflecting surface 160, machinedor otherwise formed in the proximal end of segment 102; it is closed bythe distal end of segment 106. By forming the distal end of segment 106in a convex shape, the volume of this cavity 208 may be reduced; byextending the edge radially over the edge of the passageway 150, the rod194 is precisely positioned when inserted fully into passageway 150. Theconvex extension thus serves a two-fold purpose: reducing the cavityvolume and precisely positioning the rod 194.

A very small amount of sealant/adhesive may be applied at theconjunction of rod 194 and tube 204 at sealant location 210 in contactwith abutment 206 to restrain movement of the rod 194 and/or tube 204 toone place. The cooperation of elements 204, 194, 210, 202, and 206greatly improves the ease of assembly and the long-term reliability ofthe relative position of the optical rod 194 and internal conicalreflecting surface 160, and thus the functioning of the entire probe.

In FIG. 19, a radially inward extending surface joining the proximaltermination of segment 102 forms a rod stop 212 preventing furtherextension of the optically transmissive rod 196 towards reflectingsurface 160. More particularly, the terminal end 214 of rod 196, i.e.,the rod tip, is prevented from further movement towards reflectingsurface 160 by rod stop 212. An additional rod stop surface 216 may beused if desired, or omitted. Rod stop 216 is substantially similar torod stop 206 of FIG. 18, described hereinbefore. Note that the radiallip formed at 216 may be partially removed at the site of rod 196 lightpath communication with the internal conical reflecting surface 160, inorder permit the light beam to freely pass between the rod 196 andsurface 160.

Shield 116 guides and protects rod 196 between the cap 198 and thereflecting surface 160 and through passageway 152. Rod stop 212precisely positions and limits movement of the rod with respect to thereflecting surface 160; the additional rod stop 216 may alternatively bepositioned at the distal end of segment 106 for this purpose.

Cavity 208, formed by the depression formed by internal conicalreflecting surface 160, is closed by the generally convex distal end ofsegment 106. The cavity volume is thus minimized.

Significant light path improvements within the chamber have beenrendered possible by the foregoing structural improvement illustrated inFIGS. 15-19. The improved light path, and the more precise positioningof the light path carriers--rods 194, 196--greatly increases efficiency.

Linearity and sensitivity of reflectance measurements are also improvedwith changes in the port angles relative one another. The addition of anoptical immersion fluid to the cavity has been found to significantlyincrease optical transmission and thus sensitivity within the cavity208.

In the embodiment of FIG. 4, the sense (input) light port 20 and detect(output) light port 21 to and from the chamber 18 are displacedoppositely at a 180-degree angle, and the reflectance detection lightport 26 for detecting light reflected within the chamber 18 is normallydisplaced at a 90-degree angle between light port 20 and light port 21.As shown in FIG. 3, an angle (Alpha 3) is disclosed for this purposewhich is less than 90 degrees, but greater than about 50 degrees. FIG.20 is a composite view showing for comparison the main relative portpositions for the FIG. 4 embodiment and also those for the presentimprovement.

In the presently disclosed embodiment of FIGS. 16-19, as illustrated inFIG. 20, the sense port is located at 0 degrees, position 218 and thedetect port is located at 180 degrees, position 220, generallycorresponding to the position of light guides 20 and 21 of FIGS. 3 and4. The reflection port of FIGS. 3 and 4 is shown at 222. The reflectionport of the present disclosed embodiment is displaced within a range offrom about 5 degrees at position 224 to less-than about 45 degrees(relative the sense light, 218) at position 226, preferably within arange of about 5 to about 30 degrees. The angle is more particularlypreferred at between about 5 degrees (position 224) and about 20degrees, or within a narrower range centered around about 15 degrees(position 228). In FIG. 20, the minimum angle for locating a reflectanceport at 224 is given at 5 degrees; the actual size of the light rod isincreased for emphasis, thus locations 218 and 224 are shown asoverlapped when in actuality they would lie adjacent, but separated fromone another.

The invention is not to be limited by the illustrative, preferredembodiments disclosed herein. Numerous modifications and variations willbe apparent to those skilled in the art. Other equivalent lightcommunications pathways may be employed; equivalent materials may besubstituted; and equivalents of the particular methods of forming partsdisclosed may be employed without departing from the spirit and scope ofthe present invention as claimed in the appended claims.

What is claimed is:
 1. A probe for optically-based samplingcomprising:a) an elongated main body having a recessed distal end; b) anelongated extension body adapted for attachment to said main body,having an interior conical reflecting surface facing said main body; c)a sample chamber disposed between said extension body and said main bodyin said main body recess, said sample chamber further including anoptical entry and an optical exit, and a fluid entry, wherein the samplechamber is adapted to contain a fluid; d) means for directing radiantenergy from an external source to a first node located within said mainbody; e) means for communicating radiant energy from said first node toa first portion of said interior conical reflecting surface, comprisinga first conducting rod; f) means for communicating radiant energy fromsaid first portion of said interior conical reflecting surface to adetector; and g) means for admitting successive samples of such fluidinto said sample chamberwherein said means for admitting comprises anextension body central chamber which includes a necked-down portion ofreduced cross section, and said means for admitting comprises means forclosing said chamber at said necked-down portion.
 2. The probe of claim1, wherein said extension body includes a recessed bore positionedbetween a first end thereof which joins said main body and said interiorconical reflecting surface which is formed in said extension body. 3.The probe of claim 1, wherein said first node comprises transducer meansfor converting electrical energy in a first medium to optical energy ina second medium.
 4. The probe of claim 1, wherein said first lightconducting rod is a discrete rod enclosed within a first rod casing. 5.The probe of claim 4, further including a second node location withinsaid main body interposed between a second portion of said interiorconical reflecting surface and said detector, and means for directingradiant energy from said interior conical reflecting surface to saidsecond node location within said main body comprising a second lightconducting rod.
 6. The probe of claim 5, wherein said second roddiameter is greater than about 0.01 inches and less than about 0.100inches in diameter.
 7. The probe of claim 1, wherein said means fordirecting radiant energy from said source to said first node locationwithin said main body is a discrete light conducting optical fiber.
 8. Aprobe for optically-based sampling comprising:a) an elongated main bodyhaving a recessed distal end; b) an elongated extension body adapted forattachment to said main body, having an interior conical reflectingsurface facing said main body; c) a sample chamber disposed between saidextension body and said main body in said main body recess, said samplechamber further including an optical entry and an optical exit, and afluid entry, wherein the sample chamber is adapted to contain a fluid;d) means for directing radiant energy from an external source to a firstnode located within said main body; e) means for communicating radiantenergy from said first node to a first portion of said interior conicalreflecting surface, comprising a first conducting rod; f) means forcommunicating radiant energy from said first portion of said interiorconical reflecting surface to a detector; and g) means for admittingsuccessive samples of such fluid into said sample chamberwherein saidmeans for closing includes a plunger, further including means foradjustably positioning said plunger within said sample chamber.
 9. Theprobe of claim 8, wherein said extension body includes a recessed borepositioned between a first end thereof which joins said main body andsaid interior conical reflecting surface which is formed in saidextension body.
 10. The probe of claim 8, wherein said first nodecomprises transducer means for converting electrical energy in a firstmedium to optical energy in a second medium.
 11. The probe of claim 8,wherein said first light conducting rod is a discrete rod enclosedwithin a first rod casing.
 12. The probe of claim 11, further includinga second node location within said main body interposed between a secondportion of said interior conical reflecting surface and said detector,and means for directing radiant energy from said interior conicalreflecting surface to said second node location within said main bodycomprising a second light conducting rod.
 13. The probe of claim 12,further including means for reflectance detection, comprising anadditional light conducting rod displaced from and extending away froman additional surface portion of said interior conical reflectingsurface to an additional detector.
 14. The probe of claim 13, whereinsaid additional surface portion is displaced from about 5 azimuthdegrees to about 45 azimuth degrees from said first surface portion ofsaid interior conical reflecting surface.
 15. The probe of claim 12,wherein said second rod diameter is greater than about 0.01 inches andless than about 0.100 inches in diameter.
 16. The probe of claim 8,wherein said means for directing radiant energy from said source to saidfirst node location within said main body is a discrete light conductingoptical fiber.
 17. A probe for optically-based sampling comprising:a) anelongated main body having a recessed distal end; b) an elongatedextension body adapted for attachment to said main body, having aninterior conical reflecting surface facing said main body; c) a samplechamber disposed between said extension body and said main body in saidmain body recess, said sample chamber further including an optical entryand an optical exit, and a fluid entry, wherein the sample chamber isadapted to contain a fluid; d) means for directing radiant energy froman external source to a first node located within said main body; e)means for communicating radiant energy from said first node to a firstportion of said interior conical reflecting surface, comprising a firstconducting rod; f) means for communicating radiant energy from saidfirst portion of said interior conical reflecting surface to a detector;and g) means for admitting successive samples of such fluid into saidsample chamberwherein said means for admitting includes a plunger,further including electromagnetic means for actuating said plunger. 18.A probe for optically-based sampling comprising:a) an elongated mainbody having a recessed distal end; b) an elongated extension bodyadapted for attachment to said main body, having an interior conicalreflecting surface facing said main body; c) a sample chamber disposedbetween said extension body and said main body in said main body recess,said sample chamber further including an optical entry and an opticalexit, and a fluid entry, wherein the sample chamber is adapted tocontain a fluid; d) means for directing radiant energy from an externalsource to a first node located within said main body; e) means forcommunicating radiant energy from said first node to a first portion ofsaid interior conical reflecting surface, comprising a first conductingrod; f) means for communicating radiant energy from said first portionof said interior conical reflecting surface to a detector; and g) meansfor admitting successive samples of such fluid into said samplechamberwherein said means for admitting includes a plunger, furtherincluding pneumatic means for actuating said plunger.
 19. A probe foroptically-based sampling comprising:a) an elongated main body having arecessed distal end; b) an elongated extension body adapted forattachment to said main body, having an interior conical reflectingsurface facing said main body; c) a sample chamber disposed between saidextension body and said main body in said main body recess, said samplechamber further including an optical entry and an optical exit, and afluid entry, wherein the sample chamber is adapted to contain a fluid;d) means for directing radiant energy from an external source to a firstnode located within said main body; e) means for communicating radiantenergy from said first node to a first portion of said interior conicalreflecting surface, comprising a first conducting rod; f) means forcommunicating radiant energy from said first portion of said interiorconical reflecting surface to a detector; and g) means for admittingsuccessive samples of such fluid into said sample chamberwherein saidmeans for admitting comprises an interior central chamber in theextension body which chamber includes a necked-down portion of reducedcross section, and said means for admitting comprises means for closingsaid chamber at said necked-down portion.
 20. The probe of claim 19,wherein said extension body includes a recessed bore positioned betweena first end thereof which joins said main body and said interior conicalreflecting surface which is formed in said extension body.
 21. The probeof claim 19, wherein said first node comprises transducer means forconverting electrical energy in a first medium to optical energy in asecond medium.
 22. The probe of claim 19, wherein said first lightconducting rod is a discrete rod enclosed within a first rod casing. 23.The probe of claim 22, further including a second node location withinsaid main body interposed between a second portion of said interiorconical reflecting surface and said detector, and means for directingradiant energy from said interior conical reflecting surface to saidsecond node location within said main body comprising a second lightconducting rod.
 24. The probe of claim 23, wherein said second roddiameter is greater than about 0.01 inches and less than about 0.100inches in diameter.
 25. The probe of claim 23, further including meansfor reflectance detection, comprising an additional light conducting roddisplaced from and extending away from an additional surface portion ofsaid interior conical reflecting surface to an additional detector. 26.The probe of claim 19, wherein said means for directing radiant energyfrom said source to said first node location within said main body is adiscrete light conducting optical fiber.
 27. A probe for optically-basedsampling comprising:a) an elongated main body having a recessed distalend; b) an elongated extension body adapted for attachment to said mainbody, having an interior conical reflecting surface facing said mainbody; c) a sample chamber disposed between said extension body and saidmain body in said main body recess, said sample chamber furtherincluding an optical entry and an optical exit, and a fluid entry,wherein the sample chamber is adapted to contain a fluid; d) means fordirecting radiant energy from an external source to a first node locatedwithin said main body; e) means for communicating radiant energy fromsaid first node to a first portion of said interior conical reflectingsurface, comprising a first conducting rod; f) means for communicatingradiant energy from said first portion of said interior conicalreflecting surface to a detector; and g) means for admitting successivesamples of such fluid into said sample chamber;wherein said means foradmitting includes a plunger, further including means for actuating saidplunger for closing said means for admitting.
 28. The probe of claim 27,wherein said extension body includes a recessed bore positioned betweena first end thereof which joins said main body and said interior conicalreflecting surface is formed in said extension body.
 29. The probe ofclaim 28, wherein said extension body recessed bore includes an innerwall and a radially inward surface joining said inner wall to saidinterior conical reflecting surface.
 30. The probe of claim 27, furtherincluding adhesive means for joining said extension body to said mainbody.
 31. The probe of claim 2, wherein said main body includes a fluidport, further including means for fluid communication between saidsample chamber and said fluid port.
 32. The probe of claim 27, whereinsaid first node comprises transducer means for converting electricalenergy in a first medium to optical energy in a second medium.
 33. Theprobe of claim 27, wherein said means for directing radiant energy fromsaid source to a first node location within said main body is a discretelight conducting optical fiber.
 34. The method of optical sensingcharacteristics of a fluid in a sample chamber in a probe whichcomprises:a) admitting a first one of multiple samples of a fluidthrough said chamber via an entry and then closing said chamber with aplunger to form a discrete sample; b) opening said chamber entry toadmit a succeeding fluid sample to enter said chamber via said entry; c)passing an input signal to a first node within said probe, said firstnode containing an end of a first, discrete light-conducting rod; d)conducting said input signal from said first node through said first rodas light energy to a first portion of an interior conical reflectingsurface; e) reflecting said input signal from said first portion of saidinterior conical reflecting surface to a second portion of said interiorconical reflecting surface; f) collecting as an output optical signal atleast a portion of the light reflected from said second portion of saidinterior conical reflecting surface; and g) directing said outputoptical signal to a detector within said probe.
 35. The method of claim34, wherein said detector is a first detector, and wherein a reflectanceoptical signal is carried by an additional light-conducting rod from anadditional node located within said probe, further including the step oftransferring the reflectance optical signal via an optical fiber pathwayto an additional detector.
 36. The method of claim 34, wherein areflectance optical signal is carried by an additional light-conductingrod from an additional node located within said probe, further includingthe step of converting the reflectance optical signal to an electricalsignal in said additional node.
 37. The method of claim 34, wherein saiddetector comprises means for converting an optical signal to anelectrical signal, further including the step of converting the outputoptical signal to an electrical signal.
 38. The method of claim 34,wherein said first node comprises means for converting an electricalsignal to an optical signal, further including the step of converting anelectrical input signal to an optical input signal.
 39. The method ofclaim 34, wherein the output optical signal is carried by a secondlight-conducting rod to a second node located within said probe, furtherincluding the step of transferring the output optical signal via anoptical fiber pathway to said detector.
 40. The method of claim 34,wherein the output optical signal is carried by a secondlight-conducting rod to a second node located within said probe, furtherincluding the step of converting the output optical signal to anelectrical output signal in said second node.